From the Guidelines
Nicotine itself is not classified as a carcinogen, and the current evidence suggests that it does not directly cause cancer. While nicotine is the addictive substance in tobacco products, it is not directly responsible for causing cancer. The carcinogenic effects of tobacco products come primarily from other chemicals produced during combustion, such as tobacco-specific nitrosamines, polycyclic aromatic hydrocarbons, and various other toxic compounds. Nicotine does have numerous health effects including increasing heart rate, raising blood pressure, and constricting blood vessels, and it is highly addictive, leading to dependence. However, research has not conclusively shown that nicotine alone causes cancer, as stated in a study published in the Journal of the National Comprehensive Cancer Network 1.
Key Points
- Nicotine replacement therapies (NRT) are considered safer alternatives to smoking tobacco because they deliver nicotine without the carcinogenic compounds found in tobacco smoke.
- There is insufficient evidence that NRT causes cancer in humans, as reported in a study published in 2016 1.
- The use of combination NRT is recommended for smoking cessation, as it has been shown to be effective in fostering quitting and long-term cessation, with significantly less blood nicotine levels compared to smoking cigarettes 1.
- Nicotine products should still be used with caution due to their other health effects and addictive properties.
Evidence Summary
The evidence from recent studies, including those published in 2016 1, suggests that nicotine is not a direct cause of cancer. These studies have investigated the effects of nicotine on cancer and cardiovascular risks, and have found that there is insufficient evidence to support a link between nicotine and cancer. The most recent and highest quality study, published in the Journal of the National Comprehensive Cancer Network 1, provides the strongest evidence for this conclusion.
From the Research
Nicotine as a Carcinogen
- The classification of nicotine as a carcinogen is a topic of ongoing research and debate.
- According to a study published in 2003 2, nicotine is addictive and toxic but not carcinogenic in itself. However, its addictive properties lead to continued use of tobacco products, which contain many carcinogens.
- A 2014 study 3 found that nicotine induces genomic variations and promotes instability, potentially mediated by oxidative stress, implicating nicotine in carcinogenesis.
- Another study from 2014 4 discusses emerging evidence of direct contributions of nicotine to cancer onset and growth, including its ability to damage the genome and facilitate growth and spreading of transformed cells.
- In contrast, a 2009 study 5 found that nicotine replacement therapy alone was not a significant predictor of lung cancer, gastrointestinal cancer, or all cancers, suggesting that nicotine itself may not be a direct cause of cancer.
Evidence for Nicotine's Role in Cancer
- A 2022 study 6 highlights the importance of regulating the levels of carcinogens, toxicants, and nicotine in tobacco products to prevent tobacco-related cancer.
- The same study 6 notes that tobacco products present a deadly combination of nicotine addiction and carcinogen exposure, resulting in millions of cancer deaths per year worldwide.
- The 2014 study 3 identified over 6,400 somatic mutations in normal human epithelial cells exposed to nicotine, including 429 non-synonymous single-nucleotide variants, of which 158 were novel and 79 were cancer-associated.
- The 2014 study 4 suggests that the nicotinic acetylcholine receptors, which are activated by nicotine, can activate several signaling pathways that can have tumorigenic effects, and these receptors might be able to be targeted for cancer therapy or prevention.